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Tcecarenko [31]
2 years ago
12

45 The mass of an unidentified metal sphere is 133 grams. Students determine the

Chemistry
1 answer:
Lisa [10]2 years ago
7 0

Answer:

D Cobalt

Explanation:

The volume of the sphere is  40 -25 = 15 cm^3

Density = mass/volume = 133 gm / 15 cm^3 = 8.87 gm/cm^3

  which corresponds to Cobalt from the chart

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At 35.0°c and 3.00 atm pressure, a gas has a volume of 1.40 l. what pressure does the gas have at 0.00°c and a volume of 0.950 l
Leona [35]

Answer : The pressure of gas will be, 3.918 atm and the combined gas law is used for this problem.

Solution :

Combined gas law is the combination of Boyle's law, Charles's law and Gay-Lussac's law.

The combined gas equation is,

\frac{P_1V_1}{T_1}=\frac{P_2V_2}{T_2}

where,

P_1 = initial pressure of gas = 3 atm

P_2 = final pressure of gas = ?

V_1 = initial volume of gas = 1.40 L

V_2 = final volume of gas = 0.950 L

T_1 = initial temperature of gas = 35^oC=273+35=308K

T_2 = final temperature of gas = 0^oC=273+0=273K

Now put all the given values in the above equation, we get the final pressure of gas.

\frac{3atm\times 1.40L}{308K}=\frac{P_2\times 0.950L}{273K}

P_2=3.918atm

Therefore, the pressure of gas will be, 3.918 atm and the combined gas law is used for this problem.

4 0
3 years ago
Read 2 more answers
Use the standard reaction enthalpies given below to determine ΔH°rxn for the following reactionP4(g) + 10 Cl2(g) → 4PCl5(s) ΔH°r
weqwewe [10]

Answer:

Therefore  \bigtriangledown H^\circ_{rxn}= -1835 KJ

Explanation:

Enthalpy is denoted by H.

Enthalpy: Total heat change in a chemical reaction is called enthalpy.

The change of entalpy of a reaction is denoted by \bigtriangledown H^\circ_{rxn}

Hass's Law:The change in enthalpy of any process can be determined by calculating the sum of change in enthalpy of each of the steps involved in the process.

g= gas

S= solid

P₄(g)+10Cl₂(g)→ 4Cl₅(s)       \bigtriangledown H^\circ_{rxn}=?

PCl₅(s)→ PCl₃(g)+Cl₂(g) .......(1)       \bigtriangledown H^\circ_{rxn}= +157KJ

P₄(g)+6Cl₂(g)→  4PCl₃(g).............(2)     \bigtriangledown H^\circ_{rxn}= -1207 KJ

If we flip a reaction the value of enthalpy will be change positive to negative or nagative to positive but the numerical value will be remain same.

We need rearrange the equation (1) because in the required equation Cl₂ is on the left side. So we flip the first equation.

PCl₃(g)+Cl₂(g)→PCl₅(s)......(3)          \bigtriangledown H^\circ_{rxn}= -157KJ

Multiplying 4 with equation (3)

4 PCl₃(g)+4Cl₂(g)→4PCl₅(s)......(4)          \bigtriangledown H^\circ_{rxn}=4×( -157)KJ= -628 KJ

Adding equation (2) and (4) we get

P₄(g)+6Cl₂(g)+4 PCl₃(g)+4Cl₂(g)→4PCl₃(g)+4PCl₅(s)    \bigtriangledown H^\circ_{rxn}=( -1207-628)KJ

⇒P₄(g)+10Cl₂(g)→4PCl₃(g)-4PCl₃(g)+4PCl₅(s)      \bigtriangledown H^\circ_{rxn}= - 1835KJ

⇒P₄(g)+10Cl₂(g)→ 4Cl₅(s)       \bigtriangledown H^\circ_{rxn}= -1835 KJ

Therefore  \bigtriangledown H^\circ_{rxn}= -1835 KJ

5 0
2 years ago
Round the number 6845 into three significant figures
DIA [1.3K]
6840 is the answer hope this help
5 0
3 years ago
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The change of phase from a vapor to a liquid is called _____.
dolphi86 [110]
The change of phase from a vapor to a liquid is called condensation.
Hope this helps~
4 0
3 years ago
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Which equation represents a conservation of atoms?
weqwewe [10]

Answer:

4) 4Fe + 3O₂ → 2Fe₂O₃

Explanation:

4Fe + 3O₂ → 2Fe₂O₃

In this equation the numbers of atoms are same in both side. There are four iron and six oxygen atoms are present on left and right side of equation. That's why atoms are conserved. This equation completely followed the law of conservation of mass.

Law of conservation of mass:

According to the law of conservation mass, mass can neither be created nor destroyed in a chemical equation.

This law was given by french chemist  Antoine Lavoisier in 1789. According to this law mass of reactant and mass of product must be equal, because masses are not created or destroyed in a chemical reaction.

8 0
2 years ago
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